The present invention relates to a leaf spring suspension and, more particularly, to an attachment arrangement for mounting the leaf spring to a vehicle mainframe to accommodate longitudinal movement of the leaf spring during flexing thereof through shear movement of a damper.
Various conventional vehicle suspensions include a leaf spring fabricated from a series of superimposed steel leaves. Steel leaf springs may be disadvantageous because they are relatively heavy, noisy, and subject to corrosion.
More recently, fiber reinforced resin composite materials have been utilized as a substitute for steel leaf springs. In some leaf springs of this type, a curved central section of the spring is molded from longitudinally extending fibrous material impregnated with a thermosetting resin. Separate metal end sections are attached through mechanical connectors to the ends of the curved central section. Another form of fiber reinforced resin composite leaf spring includes continuous strands of fibrous material impregnated with a thermosetting resin, which are wound around spaced bushings or pins in a loop configuration. After winding, the wound structure is placed in a mold with the parallel runs of the loop being brought together in flatwise contiguous relation while the resin is subsequently cured to provide an integral structure.
Each leaf spring is located adjacent a longitudinal vehicle frame rail underneath the body of a truck or trailer chassis. Although providing many benefits including light weight and great strength, attachment of fiber reinforced resin composite leaf springs to the vehicle frame rails may pose various difficulties.
One difficulty includes the preference for avoiding mounting arrangements that require locating apertures through the composite leaf spring. Penetration of the composite leaf spring severs the fibrous materials and correspondingly reduces the physical characteristics of the spring. Conversely, elimination or minimization of apertures further decreases the mounting versatility for particular vehicle designs as specific metal end sections are utilized for frame rail mounting. That is, each leaf spring must be specifically tailored to a specific vehicle which may decrease the versatility of each leaf spring.
Other mounting arrangements include rather complicated brackets to avoid locating apertures through the leaf spring. Disadvantageously, the bracket arrangement may be relatively heavy in weight, which may offset some of the weight advantage inherent to composite materials.
Furthermore, conventional mounting arrangements commonly provide a metal to composite interface. These dissimilar material interfaces are wear points which may weaken the composite material and reduce the life of the suspension.
Accordingly, it is desirable to provide an uncomplicated composite leaf spring attachment arrangement that accommodates various suspension members, does not require through apertures, avoids dissimilar material wear points, and is light in weight.